gistfile1.txt

// C program to verify the solution to "The Three Hats Game"
// as seen on http://www.futilitycloset.com/2015/02/17/the-three-hats-game/
// Compile with gcc -o hat-game hat-game.c
//
// Count wins: ./hat-game | grep win | wc -l
// Count losses: ./hat-game | grep lose | wc -l

#include <stdio.h>
#include <stdlib.h>

void game() {
  int r = rand();

  int a = r & 1;
  int b = (r & 2) ? 1 : 0;
  int c = (r & 4) ? 1 : 0;
  printf("a:%d b:%d c:%d  ", a, b, c);

  // How many players guessed
  int guessed = 0;
  int wrong = 0;

  // a's choice
  if (b ^ c) {
    // Saw different colors
    printf("A:- ");
  } else {
    guessed++;
    int guess = !b;
    printf("A:%d ", guess);
    if (a != guess) wrong = 1;
  }
    
  // b's choice
  if (a ^ c) {
    // Saw different colors
    printf("B:- ");
  } else {
    guessed++;
    int guess = !a;
    printf("B:%d ", guess);
    if (b != guess) wrong = 1;
  }
 
  // c's choice
  if (a ^ b) {
    // Saw different colors
    printf("C:- ");
  } else {
    guessed++;
    int guess = !b;
    printf("C:%d ", guess);
    if (c != guess) wrong = 1;
  }

  if (guessed > 0 && !wrong) {
    printf(" = win\n");
  } else {
    printf(" = lose\n");
  }
}

int main(int argc, char **argv) {
  srand(42);

  int i;
  for (i = 0; i < 10000; i++) { game(); }
}